Gamma-observable neighbours for vector quantization.

We define the gamma-observable neighbourhood and use it in soft-competitive learning for vector quantization. Considering a datum v and a set of n units w(i) in a Euclidean space, let v(i) be a point of the segment [vw(i)] whose position depends on gamma a real number between 0 and 1, the gamma-observable neighbours (gamma-ON) of v are the units w(i) for which v(i) is in the Voronoï of w(i), i.e.